3-D model of rat brain circuit created

In this file photo, a worker holds a white rat in a lab. Scientists have developed a 3-D model of a rat brain research, they report in a new study.

After six years and several million dollars, scientists have created a 3-D model of a rat brain circuit.

The accomplishment is a first step toward creating a complete computer model of the brain that will allow a deeper understanding of how our noggins work — and what causes them to malfunction, according to the scientists behind the feat.

For a starting point, researchers at the Max Planck Florida Institute are focused on how the rat brain processes information gathered by a single whisker.

They did so because studies in their lab and elsewhere have shown that a single whisker is able to detect, in complete darkness, whether a gap is safe to jump over and, if so, trigger the order to jump.

What's more, there's a specific region of the brain "that is dedicated to processing information from a dedicated whisker," Marcel Oberlaender, a researcher at the institute and the first author of a paper explaining the research in the journal Cerebral Cortex, told me today.

That region is called the cortical column, a vertically-organized series of connected neurons that form a brain circuit and an elementary building block of the cortex.

The cortex is the part of the brain responsible for many of the higher functions, such as memory and consciousness.

To build the model, the researchers studied the cortical column in awake and anesthetized rats as well as brain slices and then used computer software and other tools to reconstruct it.

"The model we built is really based on a complete reconstruction of these nerve cells," Oberlaender said. "So how the model looks in the end resembles how it would look in the real animal."

It is composed of 16,000 neurons, each of which can be divided into one of nine different cell types that has characteristic functional, structural and connectivity properties, he added.

The model can now be used to run computer simulations that show, in realistic detail, how signals flow within the brain. So, they can begin to understand, for example, what neurons fire as the rat detects the gap and decides whether or not to jump.

Until now, researchers have only been able to see how a single neuron or a small group of neurons interact during such a process. "We can now, in simulation experiments, mimic what is really going on in these circuits," Oberlaender said.

Going forward, the researchers should be able to use the methodology developed to build this model to add more parts to it, thus incorporating other brain functions such as the motor system that sends a signal down the spinal cord and makes the limbs move so that rat can jump over the gap.